Re: Fwd: Re: r365488 page faults on AMD Ryzen 9 3950X

On Tue, Sep 22, 2020 at 01:13:29AM +0300, Konstantin Belousov wrote:
> On Mon, Sep 21, 2020 at 08:57:46PM +0200, Rainer Hurling wrote:
> > Fatal trap 12: page fault while in kernel mode
> > cpuid = 31; apic id = 1f
> > fault virtual address   = 0x25407efa
> This address is very suspicious.
> 
> I cannot claim it as the fact, but most likely cause for such garbage
> pointer value is mismatched ABI between kernel and module.  In other
> words, the module was built against headers from different kernel.

For some reason clang is not complaining about a missing declaration for
vm_pager_allocate(), despite -Wmissing-prototypes in the CFLAGS...

This patch is required on top of a patched extract of the vbox sources:

--- the-freebsd-kernel.h.orig	2020-09-22 18:49:26.499329000 -0400
+++ the-freebsd-kernel.h	2020-09-22 18:49:55.317615000 -0400
_at__at_ -68,6 +68,7 _at__at_
 #include <vm/vm_kern.h>
 #include <vm/vm_param.h>        /* KERN_SUCCESS ++ */
 #include <vm/vm_page.h>
+#include <vm/vm_pager.h>
 #include <vm/vm_phys.h>         /* vm_phys_alloc_* */
 #include <vm/vm_extern.h>       /* kmem_alloc_attr */
 #include <vm/vm_pageout.h>      /* vm_contig_grow_cache */
--- memobj-r0drv-freebsd.c.orig	2020-09-22 18:49:25.010456000 -0400
+++ memobj-r0drv-freebsd.c	2020-09-22 18:49:47.462276000 -0400
_at__at_ -323,7 +323,8 _at__at_
     size_t      cPages = atop(pMemFreeBSD->Core.cb);
     int         rc;
 
-    pMemFreeBSD->pObject = vm_object_allocate(OBJT_PHYS, cPages);
+    pMemFreeBSD->pObject = vm_pager_allocate(OBJT_PHYS, NULL,
+        pMemFreeBSD->Core.cb, VM_PROT_ALL, 0, curthread->td_ucred);
 
     /* No additional object reference for auto-deallocation upon unmapping. */
 #if __FreeBSD_version >= 1000055
_at__at_ -457,7 +458,8 _at__at_
         return VERR_NO_MEMORY;
     }
 
-    pMemFreeBSD->pObject = vm_object_allocate(OBJT_PHYS, atop(cb));
+    pMemFreeBSD->pObject = vm_pager_allocate(OBJT_PHYS, NULL,
+        pMemFreeBSD->Core.cb, VM_PROT_ALL, 0, curthread->td_ucred);
 
     if (PhysHighest != NIL_RTHCPHYS)
         VmPhysAddrHigh = PhysHighest;